1. Field of the Invention
This invention relates to odorless and organic solvent-free novel waterborne latex or emulsion compositions which contain an internally plasticizing and cross-linkable monomer(s) having at least one double bond in its backbone. More particularly, though not exclusively, this invention relates both to novel latex or emulsion compositions containing a substituted or unsubstituted acrylic ester of a long-chain alkenol and a process for making the same. The invention is also directed to the utility of these novel compositions in coatings, adhesives, and inks which have essentially no volatile organic components (VOCs) and feature enhanced application and performance properties.
2. Description of the Prior Art
Recent Congressional enactments have forced coatings manufacturers to develop new coating formulations that contain low VOCs yet feature good performance properties. However, attempts at developing new formulations that contain environmentally acceptable low VOCs have only resulted in formulations with poor performance characteristics which are also economically unattractive.
One problem encountered by the coatings manufacturers is the development of formulations containing low VOC-coalescing aids or plasticizers. For instance, emulsion polymers are currently formulated with coalescing aids or plasticizers in order to form films at and below ambient conditions yet dry to films of sufficient glass transition temperature (Tg) to perform adequately at and above room temperature. In general, the ability of emulsion polymers to form or coalesce into film is governed by the minimum film forming temperature (MFT) of the polymer in question, which typically approximates Tg of that polymer. Thus, there is a dilemma, i.e., low MFT polymers are required in order to exhibit coalescence, flow, and surface wetting properties. However, if the polymer remains soft and tacky, the coatings are not usable. Therefore, it is necessary to develop a technology in which coating formulations contain suitable ingredients with an initial low MFT, followed upon application forms nontacky, durable, hard, and water resistant surfaces having a Tg significantly above their MFT.
There are few references in literature which describe low MFT coating compositions which cure to form high Tg films. One such example utilizes a terpolymer binder known as Vinamul 3692, which is used in solventless paints. The terpolymer is formed from ethylene, vinyl acetate, and acrylated ethylene vinyl acetate. Although the physical properties of the paint films are generally good, the latex synthesis involves the use of ethylene in high pressure reactors. Such a manufacturing protocol is not available to most latex manufacturers and is not cost effective.
There have been many other reports that disclose coatings compositions that cure or dry at ambient conditions into durable products. For example, vinylic derivatives of auto-oxidizable drying oils have been synthesized, which are formulated into crosslinkable emulsion compositions. However, these emulsion compositions still required the use of VOCs for film formation and formulation into usable coatings. Moreover, the polymers possessed other drawbacks, i.e., the free radical polymerizations of vinyl monomers of high iodine number oils are kinetically unfavorable and the products exhibit moderate to marked incompatibility.
Various other coating compositions which cure under ambient conditions are known in the prior art. A few such examples involve curing by a chemical reaction such as epoxide-carboxylic acid reaction, isocyanate-moisture reaction, polyaziridine-carboxylic acid reaction, and activated methylene-unsaturated acrylic reaction.
There are also literature references which disclose derivatives of fatty compounds suitable in the formation of coatings. For example, acryloxymethyl substituted fatty compounds have been claimed to be useful in radiation curable coating formulations and as binders in inks. Acrylate esters of castor oil have also been reported to be potentially useful as binders in coatings and other applications.
However, none of these references discloses use of an internally plasticizing and crosslinkable long-chain alkenol monomer for the formation of coating formulations. In addition, none of the references discussed above utilizes inexpensive and readily available acrylate or other ethylenically unsaturated esters of long-chain alkenols to form latex or emulsion compositions. Furthermore, none of the references mentioned above describes latex or emulsion compositions featuring low MFTs that cure to above ambient Tg without the use of any VOCs and yet featuring enhanced properties.
Therefore, it is an object of this invention to provide novel compositions having low VOCs and low odor which are suitable for forming coatings, adhesives, and inks formulations comprising an internally plasticizing and crosslinkable long-chain alkenol monomer. An additional objective of this invention is to provide a process for the synthesis of the novel latex or emulsion compositions. Yet another objective of this invention is to provide a variety of utilities for these novel compositions. Such utilities include as a binder in coatings, adhesives, and inks formulations featuring enhanced properties yet contributing zero VOCs. The compositions of the present invention have no precedence in the prior art.